Pneumatic hammer



April 3, 192.8.

R. H. TUCKER PNEUMATIC HAMMER Filed Oc'b. 29. 1924 2 Sheets-Sheet l.

April 3, 1928. 1,665,046

- R. H. TUCKER PNEUMATI C HAMMER Filed Oct. 29, 1924 2 Sheets-Sheet 2 the cylinder 20 are for a purpose hereinafter described.

The controlling mechanism of the valve 10 is as follows:

, A stem 55 is secured to or formed integral with the hammer valve -10 and is preferably screw threaded at one end 56 on which a nut 57 is adjusted by means of the wrench head 58. A spring 59 encircles the stem 55 and bears on the nut 57 and the spider 9. A second spring 60 is also mounted on the stem and bears against the spider and the valve head42. Y

The anvil 65 is constructed with a cylindrical interior chamber 66 and has the usual face 67 to contact with the hammer face 68.V

The anvil has the usual stem 69 sliding in the neck 27 of the cap 24. The spring 7 0 bearing against the anvil and the neck; is of the usual construction. A stop nut 71 is shown secured `by screw threads 72 to the lower end of the stem 69'. shown mounted in a socket 74 in the anvil stein;

The operation of my hammer is as follows Presuming the various moving elements are in the position shown in Fig. 1, oompressed air will be introduced into the piston cylinder 1 in the usual way. This air willy press on the wrench head 5S, and piston head 33, forcing them downward. The effective area of pressure is equal to the cross section of the piston cylinder 1. In this movement the valve head 42 is maintainedv in contact with'the piston head 33 and the ports 13 are closed as shown in VFie'. 1. The pressure ofthe spring 60 perb forms part of this function or maintaining the ports 43 closed as does also the pressure of the air on the wrench head 58.

By prearranged adjustment of the nut 57, the hammer valve 410 will be carriedV down until the compression of the spring 59 is sufficient to retard its movement. As the piston is still traveling the ports 43 will be opened as .shown in Fig. 2. This action allows the compressed air from the. piston ycylinder 1 to flow through the interior of the tube 11 into the chamber 66 inthe an-.

vil.` `In the action above mentioned, the

valve 4a is drawn upward until its coni-- cal surface L16 seats on the conical surface 47 of the hammer 85. The action above described of opening the hammer valve to allow compressed air from the piston cylinder 1 to the anvil chamber 66 preferably takes place immediately before the hammer stiilresthe anvil. VAs the anvil is thrown downwardly by the impact of the hammer and the hammer retarded the vcompressed air fills the whole of the lower portion of the hammer cylinder 20. There is therefore a large-area ofk the hammer against which the compressed air acts. This forces A tool 72 is `the piston cylinder.

the hammer upward. The relative conipressive force of the springs 59 and 60 is so adjusted that the lower spring 60 will force the valve hea-d 42 into contact with the piston head at the desired positionin the return stroke, thereby closing the ports 43. This movement of the liammei' valve 40 downward in relation to the moving piston 31 and its connected hammer 35 opens the valve 4a and allows the compressed air in the lower part of the hammer cylinder 20 to exhaust around the valve 44 through the annular space 49, through the ports 50 in the lower portion 32 of the sleeve, and through the exhaust ports 52 in the hammer cylinder 20. These ports 52 and 50 are always open so that the air in the eX- haust chamber 51 is normally at atmospheric pressure. n

As above described, by adjustmenty of the nut 57, which is readily actuated by means Y 1n these figures, 101 is an integral casing inwhich the upper part 102 forms a piston cylinder or chamber and the lower part 103 forms a hammer cylinder or chamber, formed with a larger diameter than A cap 104C is, screw threaded on the lower Vend of the hammer cylinder as indicated at 105 and has a'necl 106. At the upper end of the piston cylinder a handle head 107,` is. attached preferably by a'screw threaded connection 108. This has an inlet port 109 controlled bythe sual throttle 110. Through the handle head is a screw threaded aperture 111 for a purpose which will be hereinafter described. Sliding in the piston cylinder is apiston 112 withV a sleeve 113 connected to an integral hammer 11-1. Both the piston andthe hammer have piston rings of the usual type on their peripheries. Ananril 115 is mounted'in the lower end of the hammer cylinder and has a socket stem 116 sliding in the necl'of the cap. A spring 117 returns theA anvil to its upper position after the hammer stroke in the usualmanner.

Slid-ably mounted in the sleeve 11? is a valve 11S comprising an enlarged cylindrical section 119 at the upper end and a reduced preferably cylindrical section 120 at the lower end. A valve head 121 formed integral with the section 119 engages the bach face of the piston 112 as indicated in Fig.

from the chamber 123 `at the rearof the piston to a duct 124 through the center of the valve 118 which leads to the lhamn'ier chamber 125 at the front of the hammer as shown in Fig. 3. A conical valve head 126 is preferably screw threaded en the lower end of the reduced section 120 of the valve 118 and its beveled face 127 contacts with a similar beveled face 123 of the hammer 114 as shown in Fig. 3. The compressed air from the chamber v123 thus passes to the recess 129 in the anvil 115. An yannular space forming an exhaust passage 130 is formed between the exterior of the reduced sect-ion 120 and the hammer 114 and sleeve 113. Ports 131 lead through the sleeve 113 to an exhaust chamber 132 between the sleeve 113 and the casing 101.k From this chamber exhaust ports 133 lead -to the atmosphere.

Formed preferably integral with the valve 118 is a stem 134 having at the upper end thereof a piston 135 preferably screw threaded on the upper end thereof which reciprocates with the piston in the spring cyl.- inder 136. This cylinder is preferably screw threaded as indicated at 137 to allow threading through the screw threaded aperture 111 in the handle head 10T. Lock nuts 138 are used to secure the cylinder in desired adj usted position. At the upper end of the cylinder is a closure capA 139 preferably screw threaded to the outside of the cylinder 136 and has an interior projection 140 forming a seat for the upper spring 141. The cap is preferably maintained from turning by a set screw 142 and is squared to form a wrench hold. At the lower end of the spring cylinder is a lower cap 143 preferably threaded on the outside of the cylinder 136 and has a collar 144 extending up in the cylinder. The stein 134 reciproeates through the collar 144. A lower spring 146 is mounted between the collar 144 and the piston 135.

The operationof the pneumatic hammer of Figs. 3 and 4 is as follows:

Presuming the parts are in the position of Fig. 3, compressed air is introduced in the usual manner to the piston chamber 123 and is of substantially constant pressure7 being regulated by the usual throttle 110. The compressed air acts on the piston 112 and drives it downward into striking position with the anvil as shown in Fig. 4. The valve 118 altho lubricated has a` certain sticking action in the sleeve 113'until the spring 1.46 is compressed sufficiently to snap the valve upward as shown in Fig.l 4. This action referably takes place by prearranged adji'istn'lent of the tension of the springs just lm't'ore the hammer strikes the anvil. Compressed. air from the chamber 123 passes through the ports 122 and the duct 124 to the recess 129 in the anvil. As the anvil is driven down the air fills the whole of the chamber 125 and on account of the different.

face the hammer and anvil are driven up-v ward by the dilferentialA compressed air pressure.

On the up stroke the ports 122 remain open until the upper spring 141 is compressed ifauiiiciently to snap the valve 118 downward until the head 121 seats on the piston 112. rl`his action lowers the valve 127 and allows a free exhaust passage from the chamber )ast thel conical surfaces 127 and 123, the annular passage 130, through the port 1.31 into the exhaust chamber 132. Frein here it exhausts into the atmosphere through the port 133. The cycle is now reversed and continued as above described.

The tension of each individual spring may be adjusted by screwing the cap 139 and collar 144 in and out of the cylinder 136. rlhe length of stroke may be adjusted by screwing the whole cylinder 136 either down or up throiigh the handle cap 107.

The construction of the device of Fig. 5 as follows:

1n this compressed airis substituted for the resilient springs of Figs. 3 and 4 to trip the valve 113` rlhe stem attached to the valve is indicated by 134 and carries at its upper end a piston 135. The handle head is indicated bv 107 having a screw threaded aperture 111. ln this is mounted a screw threaded cylinder 136 having screw threads 137. The lock nut 138 secures the cylinder in adjusted position. A cap 139` is screw threaded on the upper end of the cylinder and held in position by a set screw 142.

'l`hrough'the upper part of the cylinder are apertures 15() having a closure sleeve 151 and a lock nut 152 threaded on the outside of the cylinder so that the size of the apertures may be adjusted. Below the piston a second set of apertures 153 open into-the cylinder and ma f be closed by the sleeve 154 and lock nut 155 screw threaded on the outside of the cylinder. A lower cap 156 is screw threaded on the lower end of the Cylluder and has a stutting box 157 through which the stem 134 reciprocates'. j

The operation of the device of Fig. 5 is as follows The stein 134 is reciprocated by the piston and hammer in the same manner as indicated in Figs. 3 and 4. 11s the piston 135 reciprocatcs in the cylinder 13G it forces the air in and out of the apertures and 153, but beyond these apertures it compresses the air which functions ina manner similar to the springs of 3 and 4, that is, the coin- Apressed air in the lower part of the cylinder snai s the valve 113 upwardly and the coinpre.A ed air in the upper part of the cylinder snaps it downwardly relative to the piston and hammer. i

1f the hammer is working under low pressure of compressed airin the chamber 123, it may be desirable to close or nearly close vthe apertures 150 and 153 by theclosure sleeves 151 and 154 respectively in order to increase the compression in the upper and lower part of the cylinder 136. 1t may also be desirable to do this when working under high pressure it a particularly snappy ac tion ot' the valve is desired.

It may be stated that rthe recess in the anvil has a decided function in the operation ol. the hammer. r1`he hammer is to be utilized principally by air underpressure, in which a quick stroke is required on the working' stroke and also a quick tui'n. The device in operation radically different from steam ope'ated pistons or the like in which a comparatively slow expansion ot .the steam onthe working stroke is required and also a relatively slow forcing back ot the piston by the steam on the large end ot the differential. Y

f In the first part oi'l the working stroke which may be designated as the down-stroke of applicants combined piston and hammer, the air between the hammer and the anvil is exhausted. Immediately prior to the .striking oi thehammer and the anvil the sliding valve is drawn upwardly relative to the piston and permits the working air under high pressure to pass through the valve into the space between the hammer and the anvil. This air fills the recess in the anvil with air under pressure, this pressurebeing equivalent touthat ot the driving. air and provides a relatively large quantity ot' air which may expand reely to torce the piston and anvil n into the initial position by acting on the hammer of large diameter. Tere the anvil not recessed the device could not accom-,

modate such/a large quantity of air and there being a large body of air would torce the hammer and piston upwardly, Vthe valve quickly becoming closed on its upward movement and then allowing :tree exhaust of the air.

The recess inthe anvil, by allowing a relatively large capacity ot air between lthe hammer and the anvil also 'functions to maintain the anvil pressed closely to its work and thereby eliminates to a great extent incorrect strokes ot the working tool by it becoming displaced from the work.

The applicant is 'aware of steam engine constructions or the like having' ,differential pistons in which the steam under relatively high pressure has a working stroke against the smallend of the piston and by means ot a slide valveV longitudinally through the piston gives a return stroke by action on the large end of the piston, however, it is readily manifest that applicants construction of a pneumatic hammer is radically dit ferent from such types of mechanism.

Various changes may be made without devalve, ports in the casing to exhaust air from l the rear oitthe hammer, and an anvil having a recess in the casing positioned to be struck by the hammer, the recess forming an air space adjacent tlievtace ot the hammer when the blow is struck. i

2. A pneumatic hammer comprising in combinationa piston, awhammer connected thereto, a casing in which the piston and hammer operate, a reciprocating valve opera-ting through the piston to the tace of the hammer,means i'esiliently connected to the casing to reciprocate the valve and thereby admit compressed air 'tromthe back ot' the piston to the frontotthe hammer and to exhaust the air from in front ot thehammer and an anvil positioned at the end of the casing to be struck by the hammer, lthe `anvil having a recess opposite the end of the valve when the hammer strikes the anvil.

3. 1n a pneumatic hammer, a casing, a head on the casing, a piston with a hammer connected thereto'reciprocating in said c'as ing, a reciprocating valve operating through the piston and hammer, astem on theV valve, a cylinder having screw threaded engagement with the casing head, a piston on the stem, aresilient.medium between the piston and the top and bottom ot the cylinder' to actuate the valve and an anvil in the casing positioned to bev struck by the hammer.

4. A pneumatic'hammer having a casing with va differential piston-and hammer connected'by a tubularvsleeve, a tubular valve slidably mounted .in the sleeve extending through .the piston and hammer, having apertures adjacent the piston .end and being open at the hammer end, means to flowl a gas into the piston end of the casing', means to exhaust the gas from in` front oi' the hammer to the back and outwardly through the casing, an anvil. slidably'` mounted' inv the casing in front of the hammer, andmeans to slide the valve in the sleeve, the sleeve forming a. closure for the said apertures.

5. A pneumatic hammer Vcomprising in combination a casing having a'piston and hammer of `different diameters connected by a tubular sleeve, al tubular valve having lateral apertures adjacentl the piston end, slidable in the sleeve and having an open end adjacent the hammer, there Vbeing an annular chamber between the sleeve and the valve at the hammer end, and exhaust ports through yau the sleeve and through the casing in lback of the hammer, a valve closure structure on the end of the tubular valve having e11 gagement with the hammer and forming a 5 closure for the annular chamber, means to reciprocate the valve in the Sleeve on Jche reciprocating motion of the piston hammer and sleeve, the said reciprocating motion closing the apertures leading into the tubular valve and closing the passage to the an- 10 nular chamber, and an anvil slidably mounted in the casing forward of the hammer.

In testimony whereof I have signed my name lto this specification.

RALPH H. TUCKER. 

